This application relates to wrenching tools, and, in particular, to torque-measuring and recording wrenches.
Various types of torque wrenches are known. One common type of mechanical torque wrench is what is known as a “click”-type wrench which generates an audible sound, such as a “click,” when a predetermined value of applied torque is reached. Such wrenches are disclosed, for example, in U.S. Pat. No. 4,485,703. In this type of wrench, when a predetermined set force is transmitted by the wrench to a workpiece, certain parts within the wrench move rapidly from a normal position to an actuated position in a manner such as to generate an audible click-like sound and tactile sensation to signal the operator that a predetermined set torque has been reached. The predetermined torque is set by the operator by rotating coaxial, telescoping tubular parts, so that as one part is rotated relative to the other it advances axially relative to the other along scale indicia, in the nature of a micrometer. Such wrenches have the advantage that their manner of use is simple and highly intuitive, so that the wrenches can easily be used with little or no training. Additionally, with this type of wrench, the operator can always see where the scale is set so that he can always ascertain the predetermined set torque value while the wrench is in use.
Other types of mechanical torque wrenches have gauges with one or more pivoting dials. One such wrench has two dials, one of which tracks the applied torque both up and down, and the other of which tracks the applied torque only up, so that it registers the peak torque applied.
Various types of electronic torque wrenches are also known which utilize electronic circuitry for measuring and/or indicating torque values. Such electronic devices may have the advantage of being more precise or accurate in setting predetermined torque values and in measuring applied torque. However, such electronic torque wrenches are typically much less intuitive to use than the mechanical torque wrenches described above. Such wrenches typically have a keypad with multiple keys which are capable of a number of specialized functions, many of which may rarely, if ever, be used by a particular operator. Considerable training is required to master the operation of such wrenches and the basic operational functions may be very non-intuitive. Also, in order to simultaneously display both a pre-set torque value and an applied torque value, such electronic wrenches must have relatively complex and expensive displays. While wrenches with more simplified and inexpensive displays are known, they typically register a display of the preset torque while it is being set, but then, after the setting function is accomplished, the display returns to zero in preparation for recording the applied torque during use of the wrench. If the operator puts the wrench down after setting the predetermined torque and returns to it later for use, he will have to typically perform some keypad function in order to view the preset torque. Also, such electronic wrenches lack the familiar audible/tactile indication when the predetermined set torque value is reached, and may provide some other type of visible and/or audible indication, or even require that the user watch a display.